This invention pertains to semiconductor processing techniques and more particularly to process techniques utilizing photo-definable layers to create desired structures for semiconductor devices.
The use of organic photoresist polymers as photo-definable mask layers in photolithography processes for the manufacture of semiconductor devices is well known. Typically, organic photoresist materials are used to form temporary surfaces that are removed after desired patterns have been transferred to a semiconductor substrate. The steps utilized to transfer a pattern to the semiconductor substrate often include coating a semiconductor wafer with a liquid organic photoresist layer, exposing the photoresist layer to a light source in a patterned manner, developing the photoresist layer with a liquid developer solution to remove unwanted portions of the photoresist layer, utilizing the remaining portions of the photoresist as an etch mask, and removing these remaining portions of the photoresist after the etch is completed.
It has been previously contemplated to utilize dry processing techniques for forming photo-definable layers to replace the liquid coating and developing steps used for traditional organic photoresists. Example materials that have been proposed for such dry processing techniques are organosilicon resists, such as plasma polymerized methylsilane (PPMS). Techniques for using PPMS as a photo-definable layer has been described in the following articles: Joubert et al., Journal of Vacuum Science Technology, B 12(6), pages 3909–3913 (November/December 1994); Weidman et al., Applied Phys. Lett., 62(4), pages 372–374 (25 Jan. 1993) Joshi et al., SPIE, Volume 1925, pages 709–720 (Jan. 1993); Joubert et al., SPIE, Volume 2195, pages 358–371 (1994); Weidman et al., SPIE, Volume 2438, pages 496–512 (1995). With the techniques disclosed, a PPMS layer is deposited through a plasma reaction and exposed to deep ultraviolet (DUV) light in a patterned manner to convert the exposed regions of PPMS to a photo-oxidized siloxane called PPMSO. Next, the non-exposed PPMS portions may be removed, for example with a chlorine plasma etch, leaving the PPMSO portions as a hard mask layer for further processing.